Forced expression of HDAC3 kills neurons selectively. Primary neuronal and non-neuronal cells and cell lines were transfected with plasmids encoding HDAC3-Flag or GFP. Effect of elevated HDAC3 expression on cell viability was evaluated. A, Immunofluorescence images of CGNs transfected with HDAC3-Flag and later switched to HK or LK medium for 24 h. B, TUNEL staining of HDAC3-Flag transfected CGNs after treatment with HK or LK for 24 h. C, Quantification of viability in primary cultures. CGNs, cortical neurons (Cort), and kidney fibroblasts (KF) were transfected with HDAC3 or GFP-expressing plasmids. Eight hours after transfection, CGNs were switched to either HK or LK medium and cortical neurons were either left untreated (Un) or treated with HCA. Kidney fibroblasts were left without additional treatments. D, Quantification of viability in cell lines. HT22, HeLa, and HEK293 cells were transfected with HDAC3 or GFP. Viability was quantified 32 h after transfection and compared with control cultures transfected with GFP. *p < 0.001.